How did 7th Avenue come to get one of the few curves in the city???

The bottom of this photo is Thomas Road. The 7th Avenue curve is in the middle of the photo. Notice how 7th Ave seems to be getting closer to where it should be as you head south. If this photo showed McDowell Road, you would see that the 7th Avenue "error" originates there. It doesn't seem to be an instance of a road going around a natural feature (as, for example, the curve on 3rd Avenue between St. Joseph's Hospital and Park Central, which accommodated a pond on my grandfather's dairy farm). No, 7th Avenue's westward wander looks like a surveying error. How could a surveyor make such an error? Easy, if he was from California.

If, a century ago, you were a young surveyor who was born and raised in Los Angeles or San Francisco, you would know that, when you want to survey a line straight north, you must adjust for the fact that magnetic north is about 12 degrees off of true north. So, if you are using a compass, you make your adjustment. Magnetic north moves around over the years, by the way.

Now, if you happened to get a quick street surveying job in Phoenix (professionals traveled back and forth by train quite frequently), it might not occur to you that the adjustment in Phoenix is 11 degrees, not 12. If you failed to realize that and adjust for it, you would make about a one degree error westward, which is 7th Avenue's condition. By the time the city grew above Indian School Road, so many property owners between McDowell and Indian School had built to that line that a correction would simply have cost too much. The happier solution: the 7th Avenue curve.

Got a better theory? Mine is indeed based on the true north adjustment difference between L.A. and Phoenix in about 1900.

Whatever the reason for its presence, the curve is cool. Why? It is a welcome break from the deadly, if useful, grid of the city. It is a quirk, a zany little sidestep, a bending of the bars for an escape. Humans happen to like curves. Curves mean life and energy. You like driving into it. The line-of-sight properties that you see as you approach the curve would be good places for major structures.

By the way, see the oddly un-gridlike street just east of 7th Avenue, and just south of Indian School (just south of the present Post Office)? That curly street is the remnant of a canal bank. I believe the canal was taken out in the early 1950s.

Better theory, outright corrections or general comment? Send a note and we'll put up a comment board: burke@goodgovernment.org